Coupling



FIG. 1 is a top, left perspective view of a coupling showing my new design;

FIG. 2 is a front view of FIG. 1, the rear view being identical to the front view;

FIG. 3 is a left side view of FIG. 1, the right side view being identical to the left side view;

FIG. 4 is a top view of FIG. 1; and,

FIG. 5 is a bottom view of FIG. 1. 

The ornamental design for a coupling, as shown and described. 